This invention relates to electrical testing devices and, more particularly, to hand-held devices for testing electrical circuits, wires and the like.
Prior electrical testing devices include single function test devices. These devices typically include a single probe needle or the like extending from one end of the device and a single lead wire extending from the other end of the device. A clip, such as an alligator clip, is typically joined to the lead wire and the clip is typically connected to a ground. Thus, when a circuit is probed by the probe needle, a two point connection to the circuit is established.
There are two problems with these single function test devices. First, it is often difficult to tell whether the connection to the ground is a good connection. Often, there may be paint, corrosion, rust, etc. built up on the ground and this could prevent good contact between the clip and the ground. Thus, if someone is checking a circuit when there was a poor connection between the clip and the ground, the device will not give a reading (typically indicated by an incandescent bulb or lamp) in the circuit even if the circuit does have power. It is thus sometimes difficult to distinguish between an open circuit and a grounded circuit. Second, the two point connection of these single function test devices can only give an indication of one circuit condition at a time.